Instruction.hs

-- geniserver
-- Copyright (C) 2011 Eric Kow (Computational Linguistics Ltd)
--
-- This program is free software; you can redistribute it and/or
-- modify it under the terms of the GNU General Public License
-- as published by the Free Software Foundation; either version 2
-- of the License, or (at your option) any later version.
--
-- This program is distributed in the hope that it will be useful,
-- but WITHOUT ANY WARRANTY; without even the implied warranty of
-- MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-- GNU General Public License for more details.
--
-- You should have received a copy of the GNU General Public License
-- along with this program; if not, write to the Free Software
-- Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.

module NLP.GenI.Server.Instruction (ServerInstruction(..))
where

import Control.Applicative ( (<$>), (<*>) )
import Text.JSON

data ServerInstruction = ServerInstruction
    { gParams    :: [String]
    , gSemantics :: String
    }

instance JSON ServerInstruction where
    readJSON j = do
        jo <- fromJSObject `fmap` readJSON j
        let fieldOr def x = maybe def readJSON (lookup x jo)
            fieldOrNull   = fieldOr (return [])
            field x       = fieldOr (fail $ "Could not find: " ++ x) x
        ServerInstruction <$> fieldOrNull "params"
                          <*> field "semantics"
    showJSON x = JSObject . toJSObject $
        [ ("params",    showJSONs $ gParams x)
        , ("semantics", showJSON  $ gSemantics x)
        ]